Electrode for a li-ion battery having a polyether-siloxane copolymer as binder

Abstract

The object of the invention is an electrode for a Li-ion battery, which contains a crosslinked polyether-siloxane copolymer (V), which can be prepared by crosslinking of siloxane macromers (S) having the average general formula (1):HaR1bSiO(4-a-b) / 2  (1),where R1 is a monovalent, SiC-bonded C1-C18 hydrocarbon radical which is free of aliphatic carbon-carbon multiple bonds and a and b are nonnegative integers, with the proviso that 0.5<(a+b)<3.0 and 0<a<2, and that at least two silicon-bonded hydrogen atoms are present per molecule, by means of polyether macromers (P) containing at least two alkenyl groups per molecule and optionally further compounds (W) containing alkenyl groups, with polyethylene glycols functionalized by one allyl group being excepted from the compounds (W) as binder; and also a process for preparing a crosslinked polyether-siloxane copolymer (V) as binder for the electrode in a Li-ion battery in a crosslinking step.

Description

BACKGROUND OF THE INVENTION[0001]The invention relates to an electrode for a Li-ion battery, which contains a crosslinked polyether-siloxane copolymer composed of polyether units and siloxane units as binder.[0002]The development of higher-performance electrode materials for Li-ion batteries, in particular anode materials, at the same time requires the development of compatible binder systems. The PVDF used for graphite electrodes is not suitable for use in Si-containing electrodes because of its chemical instability. This is reflected in poor electrochemical cycling behavior.[0003]Binder systems which can be processed in an aqueous medium, for example, Na-CMC, polyvinyl alcohols or acrylates, have been described as an alternative. Because of their reactivity toward the lithiated (loaded) active material, for example Li-silicide, or the usually protic solvent used for processing, these are not suitable for the processing of Li-laden active materials.[0004]US 2012 / 0153219 describes t...

AI Technical Summary

Benefits of technology

The patent is discussing a new type of material that is stable and can be used in batteries. This material can hold lithium, which is important for making batteries, and it can be worked with other materials to create even better batteries. This material can be made into a coating for the anode of batteries, which is the part that holds the lithium. Overall, this material helps to create more durable and reliable batteries.

Problems solved by technology

The PVDF used for graphite electrodes is not suitable for use in Si-containing electrodes because of its chemical instability.

This is reflected in poor electrochemical cycling behavior.

Because of their reactivity toward the lithiated (loaded) active material, for example Li-silicide, or the usually protic solvent used for processing, these are not suitable for the processing of Li-laden active materials.

A substantial disadvantage of the binders described in US 2012 / 0153219 is the preparation of the side-chain-modified siloxanes containing Si—H groups, which precedes the actual crosslinking and represents an additional process step.